1. Field of the Invention
The present invention relates to a coupling wherein a thin film 16 for sealing an opening 15 of a plug 10 attached to a sealed container 12 is broken by a cutter 34 provided on a socket 20 when the plug 10 is connected to the socket 20.
2. Description of the Related Art
There have conventionally been known automatic vending machines or manual suction machines of the bag-in-box type (hereinafter referred to as "BIB type") in which plastic-made flexible containers filled with drinks such as coffee and juice are transported in boxes made of corrugated cardboard.
According to the machines of the BIB type, there is no need to collect empty containers, unlike the prior art. Thus, the running cost of the machines can be reduced, and an excellent sanitary condition can be maintained since the fluid in the container is not exposed to the air.
Japanese Utility Model Disclosure Hei 3-93687 filed by the applicant of the present application discloses a coupling employed to remove by suction fluid filled in the container.
This coupling comprises:
a plug attached to a sealed container and provided with an opening; and PA1 a socket engaged with the plug and accommodating a valve, PA1 wherein the plug has an annular projection formed on an outer peripheral surface of a main cylinder of the plug, PA1 the socket has a cutter section for breaking a thin film for sealing the opening of the plug, when the socket is connected to the plug, and a sleeve rotatably engaged with an outer peripheral surface of a main cylinder of the socket, PA1 the outer peripheral portion of the socket is provided with a lock ring situated in a direction perpendicular to the axis of the socket and straddling the axis of the socket, the lock ring having a free end portion projecting from the outer peripheral portion of the socket via a compression coil spring, and PA1 the inner peripheral portion of the lock ring is provided with a projection engageable with the annular projection from the side face of the annular projection.
This coupling, however, has a problem in that a high resistance occurs when the plug is connected to the socket, and, in particular, a sliding resistance of an O-ring for sealing between the inner peripheral surface of the plug and the outer peripheral surface of the socket is high. Consequently, the coupling between the plug and socket cannot smoothly be performed.